1. Field of the Invention
The invention pertains to a turret comprising a rotating joint and an angular velocity reduction device.
2. Description of the Prior Art
The making of tracking turrets carrying weapon systems is known in the prior art. Turrets of this type must be capable of motion in terms of both elevation and relative bearing so that they can track targets. Anti-aircraft defense turrets must be extremely agile so as to be able to track aircraft in elevation and relative bearing for close-range anti-aircraft defence. It is imperative that a turret of this type should be capable of making more than one full rotation in relative bearing when tracking a revolving target.
The prior art also includes methods in robotics for using angular velocity reduction devices comprising, on one and the same axis, a fixed, substantially cylindrical hollow part fitted with gear teeth on its internal surface, a toothed wheel of changeable shape having two teeth less than the hollow part and providing the drive at reduced angular velocity, the said devices further comprising a substantially elliptical part capable of changing the shape of the toothed wheel of changeable shape.
Angular velocity reduction devices of this type have the advantage of low mass, very high angular velocity reduction ratio and compactness. The robot arm fitted with a reduction device of this type has a wiring for the transmission of electrical signals. The wiring both powers the actuators electrically and collects data transmitted by sensors. The wiring does not allow the robotic arm to rotate completely on its axis. This does not raise any problem for a robot inasmuch as, for the performance of its work, the absolute position with respect to a fixed reference point of the robotic arm must imperatively be known with great precision. By contrast, for a tracking turret comprising detection devices and/or weapons, it is essential to possess the ability to obtain a relative reference with respect to the position of the target and not a absolute reference with respect to a fixed reference. Of course, it is possible to fit a turret with an angle encoder for example. For example, a digital angle encoder with a resolution of 16 bits is used.
3. Summary of the Invention
The turret of the present invention has an axial angular velocity reduction device, providing a high reduction ratio, the said device being associated with a rotating joint that transmits the electrical signals needed for the proper functioning of the turret without hampering its rotation in relative bearing. The low mass of the angular velocity reduction device makes possible the construction of highly agile, low-inertia turrets. The reduction in the volume of the turrets makes them smaller and therefore less easily identifiable by the enemy.
Furthermore, since the angular velocity reduction device is on the rotational axis of the turret, it is easily interchangeable. The velocity reduction device can be suited precisely to the reduction ratios required and the mechanical power values that it has to transmit. The angular velocity reduction device will be chosen according to the weapons system used with which the turret is equipped, and especially according to the mass of the said weapons system, as well as according to the the maximum rotational velocity and, consequently, the power of the drive motors.
Thus, for each weapons system it is possible to make an optimum turret in which inertia and costs are reduced to the minimum.
Furthermore, an existing turret can be adapted and optimized to suit a new weapons system.
The main object of the invention is a turret with two degree of freedom comprising a rotating joint, two drive motors, each drive motor being mechanically coupled with a rotational velocity reduction device, wherein the rotational velocity reduction devices comprise a fixed, substantially cylindrical hollow part fitted with a toothing on its inner surface, a toothed wheel capable of changing its shape, comprising fewer teeth than the hollow part, coupled mechanically with the part of the turret that has to be driven and a substantially elliptical part coupled mechanically with the toothed wheel by a ball bearing, the said substantially elliptical part being capable of changing the shape of the toothed wheel so as to establish contact between the wheel and the hollow part at two opposite points.